Air compressor



Oet. 22., 1929. n. P. PEscARA 1,732,593

A AIR COMPRESSOR (Filed April-v6, 1927 a'tented Oct. 22, 1929 AIR GOMPRESSGR Application tiled April 6, 1927, Serial No. M1554, and in France April 8, 1926.

My invention relates to improvements in air compressors of the type in which two compressing pistons are driven directly by internal combustion and more particularly to the stabilization and regulation of such an apparatus. s

ln a compressor of this character the piston stroke is determined solely by the amount of load the pistons are subjected to during their displacement and the object of the invention is, first, to render the pistons more stable in operation and independentl of wide variations in load, and, second, to render said pistons sutiiciently iiexible in operation 'to function satisfactorily whether the said variations in load be permanent or transient.

Other objects of my invention will be obvious to those skilled in the art in the following specification when taken in connection with the accompanying drawing in whichi p Fig. 1 is a sectional elevation of my apparatus;

Fig. 2 is a similar view of a modification thereof; and

Fig. 3 is a view of the mechanism for simultaneously regulating the admission valve and the distributer.

'lhe mechanism forming the subject of this invention is particularly,adapted to be used with my compressors disclosed and claimed in my co-pending applications Serial No'. 181,553, iled April 6, 1927, and Serial No. 177 ,939, filed March 24, 1927, respectively, and this application forms a continuation thereof.

Briefly, it will be remembered, that the apparatus in the lirst of the above mentioned applications. consisted' of a central motor cylinder 10 (Fig. 1) furnished with admission openings 11 and exhaust openings 12, compressing cylinders 18 and 14 with compressing pistons 17 and 18.

rllhe cylinders 13 and 111 are provided with openings 15 and 16 closed by automatic one way valves for taking offthe compressed air. Pistons 17 and 18 are provided with automatic one w-,ay valves 19 and 2O respectively.

rll`he pistons 'are interconnected by a synchronizing devicev as set forth in the second of the applications above mentioned and consisting brieiiy ofraclrs 21, 22, 23, 21 which are coupled in pairs by a plurality of pinions carried on the shaft 26, perpendicular to the axis of the cylinders. The pinions one of which is shown-at 25 are so designed as to give the shaft 26 less than a full turn during reciprocation of said racks.

The function of this apparatus was briefly as follows: When the explosive mixture introduced between the pistons 17 and 18 was tired, said pistons were driven in opposite directions and compressed the air in 13 and 14 pushing it through the openings 15 and 16 to the storage tank. When the energy imparted to the pistons was used up in compressing the air the pistons came to a stop. The parts were so designed that cushions of air 27 and 28, at this point, were left in each cylinder which was sufficient to drive the pistons in the reverse direction and affect the preliminary compression of the explosive` mixture subsequently introduced between the pistons since said cushions of air are under high pressure.

It will be unnecessary to go further into vdetail of the operation of the apparatus since it is disclosed and claimed in the first of my applications, above mentioned, and sufhcient has already been given for the understanding of the present invention.

Ehe same cycle of operations continues indefinitely as long as nothing disturbs the forces acting-on the pistons. lit is necessary to remark, however, that the apparatus is very easily unbalanced.

` Suppose, for example, the caloriiic value of a charge of explosive mixture should be-.

-to return the By operating t- If the ignition apparatus of the device functions according to a predetermined position of the pistons, such as disclosed in the second yof my applications, above mentioned, the pistons will der the conditions, above indicated, the explosive mixture will not be ignited, and after several oscillations of the pistons under their own momentum the apparatus will come to a stop.

If on the other hand the calorific value of the explosive mixture becomes less, then the plstons will be unable to deliver the proper quantity of air to the storage tank and the cushions of air 27 and 28 will be considerably larger and the pistons 17, 18 will be driven well beyond the firing point in the cylinder and produce the effect of a premature explosion since the force imparted to said pistons exerts a counterforce against the eifect of the explosion.

In other Words the explosion must produce a force in addition to that necessary to compress the air in the cylinders a 'force equal to the counterferce of the air cushions. If this additional force is not provided after several oscillations of the pistons, the apparatus comes to rest.

It will vthus be seen that the device above described is very unstable in operation and that it is almost impossible to successfully regulate the output of the compressor.

In the apparatus illustrated in Fig. 1, the parts have been so arranged that the quantity of` compressed air remaining in the spaces 27 and 28 at the end of the stroke of the piston is more than isnecessary to return said pistons to the point of firing in the cylinder. It follows, therefore, that the pistons 17 and 18 will move beyond the point of firing on their return stroke, as above explained. 'y

The pistons 17 and 18 tend to exert a counter-force against the force of the explosion as above described.` At this point the pistons-are given sufficient energy to overcome their counter-force and drive them back to their original position. When they again reach the end of their stroke an abnormal lamount of air is forced into the storage tank and sufficient air remains in the spaces 27, 28 istons -past the firing point. e machine in such a manner, that is, producing an excessive explosion and allowing thepistons to continually exert a counter-force against the forceof said explosion., a remarkable stability of operation not reach this position un is produced within certain limits. Such an operation of the apparatus permits the output of the compressor to be regulated by varying the quality of the explosive mixture introduced into the cylinder and it is possible to obtain nearly the stability of the normal functioning of the machine.

If it is desired to operate the apparatus with the ignition mechanism disclosed in the second of my co-pending applications above mentioned, the cylinder may be provided with a plurality of spark-plugs 29 and 30 which are adapted to be covered by the pistons 17 and 18 when they move beyond their tiring position, or during the time the pistons would tend to exert a counter-force against the explosion. The gases become pre-heated when the apparatus is operated in this manner and resembles somewhat the machines operating on the self-ignition principle. Obviously this manner of operating the compressor also greatly increases its stability of operation.

Referring to Fig. 2. illustrating my improvided compressor, the pistons 17 and 18 are provided with cylindrical chambers 32 and 33. A pair of stationary pistons 34 and 35 are carried by the cylinder heads 13 and 14 of cylinders 13 and 14 and projects into said chambers. The chambers 32 and 33 are illed with an inert gas to prevent its ignition when highly compressed, that is, a gas which will not support combustion because if air were used the lubricating materials might ignite when highly compressed. Gas taken from the exhaust pipe of the device may be advantageously employed.

The chambers 32 and 33 are completely closed and independent of the cylinders 13 and 14. In order to assure a continual sup` ply of inert gas insaid chambers, however, pistons 34 and 35 are provided with channels 38 and 39 which open into the surface of said pistons at 40 and 41. The interior walls of the pistons 17, 18 are provided with longitudinally extending grooves 42, 43, respectively, disposed in line with the-said orifices 40 and 41, the length of the said grooves being such at the moment they pass their respective oriiices a momentary communication will be established between the channels 38, 39 and the chambers 32, 33 during reciprocation of pistons 17 18.

The other elements have been given similar reference numbers to those-in Fig. 1 and since they have been described heretofore, they needl no further description.

It follows that if channels 38, 39 are connected to a tank of inert gas at the desired pressure, each time the grooves 42, 43, pass the ories 40, 41, the pressure within the `chambers 32, 33 will be renewed if for any -reason it has fallen below normal.

The apparatus just described functions in the same manner as that previously described with the exception that the pistons 17 and 18 both by the compressed air in the spaces 27 and 28 and by the compressed inert gas in the chambers 32,

ln case an abnormal explosion drives the pistons 17, 18 beyond the end of their normal stroke, the pressure of compressed air within the spaces 27, 28 becomes greatly diminished but the pressure of the inert gas within the chambers 32, 33 becomes greater. lt follows that the pistons are given suflicient energy to carry them back to the firing position notwithstanding the diminution in the air cushions at the end of their stroke.

The compensationv thus established is much more effective than that described in connection with Fig. l. The return to normal operation takes place after several abnormal reciprocations of the pistons.

'llhe regulation of the'power delivered by the machine may be accomplished in ditl'erent' ways. llt may for example be brought about as described in connection with Fig. 1 by varying the richness of the explosive mixture.

rl`he power output of the device may also be varied by varying the point in the stroke at which'the explosive mixture is ignited as described in my second application, above mentioned.

The power output of the machine may be varied by the combination of the two methods above enumerated. ln Fig. 3 is illustrated an apparatus for bringing about this result. On the needle valve of a carburetor similar to that disclosed in my first application above mentioned is disposed a roller 46 which is adapted to bear on a cam surface 47 by means of a spring 48. The cani 47 is connected to the lever 5 0 of the distributer 5l by means of a connecting rod 49.

lt follows that advancing and retarding the Vspark also varies the quality of the explosive mixture and by properly regulating the device the output of the machine may be varied over a wide range as above described.

Having thus described my invention what I claim as new and desire to secure by Letters Patr` nt isl. In an air compressor having a plurality of compressing cylinders yand compressing pistons associated with said cylinders, the

combination of means for driving said pistons simultaneously away from each other directly by means of an explosion and means including an isolated inert gas in each ofV said compressing cylinders for moving the said pistons toward each other beyond the normal length of their stroke for the purpose set forth.

2. ln an air compressor having a plurality of compressing cylinders and compressing pistons associated with said cylinders, the combination of means for driving said pistons simultaneously awayv from each other directly by 'means of an explosion, means including an isolated inert gas in each of-said cal chamber formed in each of said compressing pistons, a stationary piston projecting into each of said cylindrical chambers and an inert gas confined in said chambers whereby the said pistons are moved toward each other beyond the normal length of their stroke for the purpose set forth.

4. lin an air compressor having a plurality of compressing cylinders and compressing pistons associated with said cylinders, the combination of means for driving'said pistons simultaneously away from each other directly by means of an explosion, a cylindrical chamber formed in each of said compressing pistons, a stationary piston projecting into each of saidchambers whereby the said pistons are moved toward each other beyond the normal length of their stroke 4and means for automatically maintaining the normal pressure of said inert gas in the event of leakageA for the purpose set forth.

5. .lin an air compressor having a plurality of compressing cylinders and compressing pistons associated with said cylinders, the combination of means for driving said pistons simultaneously away from each other directly by means of an explosion, an inert gas confined in each of said compressing pistons, mea/ns including a plurality of stationary pistons for storing energy in said inert gas for moving said pistons toward each other beyond their normal length of stroke and means operated by said compressing pistons for maintaining the normal pressure of said inert gas in the event of leakage for the purpose set forth.

G. In an air compressor having a plurality of compressing cylinders and compressing pistons associated with said cylinders, the combination of means for driving said pistons simultaneously away from each other directly by means of an explosion, a cylindrical chamber formed in each of said compressing each of said cylindrical chambers, an inert gas contined in each of said chambers whereby the said pistons are moved toward each other beyond the normal length of their stroke, a longitudinally 'disposed gas inlet carried by each of said stationary pistons and adapted to communicate with the wall of its.

respective compressing piston and a longitudinally extending groove formed on the interior of each of said compressing pistons disposed in line with its respective gas inlet, each of said grooves being adapted to establish momentary communication between its respective gas inlet and cylindrical chamber during reciprocation of the said grooves for the purpose set forth.

In testimony whereof, I have signed my name to this speciication at Barcelona, Spain, this 24th day of March, 1927.

RAUL PATERAS PESCARA. 

